Mixtures suitable as fuel additives

ABSTRACT

Mixtures of at least one amine, polyamine or alkanolamine and at least one polyetheramine and their use as additives for gasoline engine fuels.

[0001] The present invention relates to mixtures which are suitable asfuel additives and comprise essentially

[0002] A) at least one amine, polyamine or alkanolamine, each of whichcarries a hydrocarbon radical having an average molecular weight of from500 to 10,000 and

[0003] B) at least one polyetheramine of the general formula I

[0004] where

[0005] m is 1 or 2

[0006] n is from 1 to 100,

[0007] R¹ is a monovalent C₂-C₃₅-hydrocarbon radical when m is 1 and adivalent C₂-C₃₀-hydrocarbon radical when m is 2, and

[0008] R² and R³ are each hydrogen, C₁-C₁₂-alkyl, C₅-C₇-cycloalkyl,C₆-C₁₀-aryl, a polyalkyleneamine radical or alkanolamine radical havingfrom 1 to 5 nitrogen atoms, where the radicals may be identical ordifferent and, together with the nitrogen atom to which they are bonded,may form a five-membered or six-membered ring in which further heteroatoms may be incorporated, and

[0009] D is C₂-C₅-alkylene.

[0010] The present invention furthermore relates to the use of themixtures and fuels for gasoline engines, which contain the components Aand B.

[0011] The carburetor and intake system of gasoline engines as well asinjection systems for metering fuel into gasoline and diesel enginesbecome increasingly contaminated by impurities which are caused by dustparticles from the air, uncombusted hydrocarbon residues from thecombustion chamber and the vent gases from the crankshaft casing whichare passed into the carburetor.

[0012] The residues adsorb fuel and change the air/fuel ratio duringidling and in the lower part-load range so that the mixture becomesricher, the combustion more incomplete and in turn the amounts ofuncombusted or partly combusted hydrocarbons in the exhaust gas becomegreater and the gasoline consumption increases.

[0013] It is known that the intake system of gasoline engines can bekept clean by adding detergents (cf. for example M. Rosenbeck inKatalysatoren, Tenside, Mineral-öladditive, Editors J. Falbe and U.Hasserodt, page 223 et seq., Thieme Verlag, Stuttgart 1978, andUllmann's Encyclopedia of Industrial Chemistry, Vol. A 16, 719 et seq.,1990, VCH Verlagsgesellschaft). Emissions and fuel consumption are thusreduced and the driving characteristics are improved. The principle ofthe molecular composition of such detergents may be described generallyas the linking of polar structures to generally relatively highmolecular weight lipophilic radicals. Typical examples of these areproducts based on polyisobutene having amino groups as polar groups, asdescribed in EP-A 244 616.

[0014] A further important additive component for fuels is a carrieroil. These carrier oils are as a rule high-boiling heat-stable liquids.EP-A 356 726 discloses esters of aromatic polycarboxylic acids withlong-chain alcohols as carrier oils. U.S. Pat. No. 5,112,364 describespolyetheramines having terminal alkylphenol or alkyl-cyclohexyl groupsas fuel additives which have in particular good valve-cleaningproperties.

[0015] WO-A 91/03529 describes the combination of detergents which carrycertain amino groups with poly-ether alcohols as carrier oils. Thiscombination in particular contributes to a lesser extent than itsindividual components to the octane requirement increase (ORI), which isdue to deposits of the fuel or the additives on engine parts. A newengine reaches its final octane requirement only after a considerablerunning time, after which said requirement may be considerably higherthan at the beginning. In general, additives should at least notreinforce this effect.

[0016] A considerable disadvantage of the stated combination ofadditives is the unsatisfactory miscibility of the detergent with thecarrier oil. Cloudy mixtures which cannot be added to the fuelsfrequently result. Phase separation frequently occurs in these mixturesafter prolonged stoppage. The distribution of the detergent in themixture is thus inhomogeneous. In practice, however, the additivepackages required are those which contain all components in dissolvedform and which can be added to the fuel in one process step.

[0017] It is an object of the present invention to provide a combinationof a detergent and a carrier oil component which, in addition to theproperties of having a valve-cleaning effect in fuels and not adverselyaffecting the ORI compared with fuels without additives, remainthoroughly miscible with one another.

[0018] We have found that this object is achieved by the mixturesdefined above, which contain a detergent A and a polyetheramine B of theformula I. We have also found the use of these mixtures, and fuels whichcontain the components A and B.

[0019] Component A

[0020] The component A is effective in fuels primarily as a detergent.Suitable components A are amines, polyamines or alkanolamines whichpossess a hydrocarbon radical having an average molecular weight of from500 to 10,000, preferably from 600 to 2,500, particularly preferablyfrom 700 to 1,500.

[0021] The hydrocarbon radical is, as a rule, branched. In general, itis a radical which is obtainable by polymerization of olefins. Theseolefins are preferably C₂-C₆-olefins, such as ethylene, propylene,1-butene, 1-pentene and particularly preferably isobutene. Bothhomopolymers and copolymers, for example polymers of from 70 to 95 mol %of isobutene and from 5 to 30 mol % of 1-butene, are suitable. As aresult of their preparation process, these polyolefins generally consistof a mixture of compounds having different molecular weights.

[0022] After chlorination, these polyolefins can be reacted with aminesin a conventional manner. However, hydroformylation of the polyolefinand amination of the resulting aldehyde and alcohol mixture underhydrogenation conditions (cf. EP-A 244 616) are preferred since thismethod leads to chlorine-free products. The amino group of the detergentA is derived from conventional amines, such as ammonia, primary amines,such as methylamine, ethylamine, butylamine, hexylamine or octylamine,secondary amines, such as dimethyhlamine, diethylamine, dibutylamine ordioctylamine, and heterocycles, such as piperazine, pyrrolidine ormorpholine, which may carry further inert substituents. Polyamines, suchas ethylenediamine, propylenediamine, diethylenetriamine,triethylenetetramine, hexamethylenediamine, tetraethylenepentamine anddimethylaminopropylamine, as well as various alkylene-carryingpolyamines, such as ethylenepropylenetriamine, may also be mentioned asstarting materials for the preparation of the detergents A. Exampleshere are alkanolmonoamines, such as ethanolamine, and alkanolpolyamines,such as aminoethylethanolamine. Among these, the polyamines arepreferred, in particular ethylenediamine, diethylenetriamine andtriethylenetetramine. However, ammonia is very particularly preferred.

[0023] Component B

[0024] The novel mixture contains, as the carrier oil, a polyetheramineof the general formula I

[0025] Specifically, the variables have the following meanings:

[0026] m is 1 or 2, preferably 1.

[0027] n indicates the number of repeating oxyalkylene units and is from1 to 100, preferably from 5 to 50, in particular from 7 to 30.

[0028] The radicals R¹ are different hydrocarbon radicals. Where m is 1,R¹ is a monovalent C₂-C₃₅-hydrocarbon radical. Straight-chain aliphaticradicals, such as n-hexyl, n-octyl, n-nonyl, n-decyl, n-undecyl,n-dodecyl and n-tridecyl, are suitable, as well as branched aliphaticradicals, such as 2-ethylhexyl, isobutyl and tert-butyl. Aryl radicals,such as phenyl, and alkyl-substituted phenyl radicals, including inparticular C₆-C₁₆-substituted phenyl radicals, such as octylphenyl,nonylphenyl and dodecylphenyl, may also be mentioned. The alkyl radicalsare preferably in the 2- and 4-position of the phenyl ring. Commercialmixtures of the positional isomers may also be used. Compounds which arepolysubstituted by alkyl are also suitable.

[0029] Where m is 2, R¹ is a divalent C₂-C₃₀-hydrocarbon radical, suchas alkylene, eg. ethylene, propylene, butylene or hexylene. However,radicals which are derived from polyphenols, such as bisphenol A(2,2-bis-(4-hydroxyphenyl)-propane, 1,1-bis-(4-hydroxyphenyl)-ethane,1,1-bis-(4-hydroxyphenyl)-isobutane,2,2-bis-(4-hydroxy-3-tert-butylphenyl)-propane and1,5-dihydroxy-naphthalene by formal elimination of the hydroxyl groupsare preferred.

[0030] R² and R³ may be identical or different. They are each hydrogen,C₁-C₁₂-alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, hexylor octyl, C₅-C₇-cycloalkyl, such as cyclopentyl or cyclohexyl,C₆-C₁₀-aryl, such as phenyl, polyalkyleneamine radicals which have from1 to 5 nitrogen atoms and are derived from polyalkyleneamines such asdiethyleneamine, triethylenediamine, tetraethylenetriamine,tetraethylenepentamine and dimethylaminopropylamine. Suitablealkanolamines are alkanolmonoamines, such as ethanolamine, andalkanolpolyamines, such as aminoethylethanolamine. Furthermore, theradicals together with the nitrogen atom to which they are bonded mayform a five-membered or six-membered ring, such as piperidine orpiperazine. The heterocyclic structure may carry inert substituents, asin 2-amino-ethylpiperazine. The ring may contain further hetero atoms,such as oxygen, as in morpholine.

[0031] D is C₂-C₅-alkylene, such as ethylene, 1,2-propylene or butylene.C₃- and C₄-alkylene groups are preferred. Where n is greater than 1, theradicals D may be identical or different. The units —(OD)_(n)— may bepresent as homopolymers or as block copolymers. However, polymers inwhich the various radicals are randomly distributed are most easilyobtainable.

[0032] The polyetheramines I are known per se or can be prepared byknown methods (U.S. Pat. No. 5,112,364).

[0033] For this purpose, an alcohol R¹—OH is generally reacted with nequivalents of an alkylene oxide in the presence of a strong base, suchas potassium tert-butylate at elevated temperatures with formulation ofa polyether of the formula II

[0034] The variables have the same meanings as stated above. Thesepolyethers are then subjected to amination by a conventional method in afurther reaction stage, generally without further pretreatment.Amination is understood here as meaning the reaction of the polyetherwith ammonia or with a primary amine or polyamine, the terminal hydroxylgroup being replaced by an amino group with elimination of water(Houben-Weyl, Methoden der Organischen Chemie, Volume 11/1, Chapter IIb,pages 108-134, 4th Edition, Thieme-Verlag, (1957)).

[0035] The novel mixtures consist essentially of the detergent A and thepolyetheramine I as component B. The mixtures contain, as a rule, from15 to 95, preferably from 30 to 80, % by weight of component A and from5 to 85, preferably from 20 to 70, % by weight of component B.

[0036] In addition, the novel mixtures may contain further components C,the amounts of C being from 0 to 40, preferably from 0 to 10, % byweight, based on the total weight of components A and B. Thesecomponents C have only a slight influence on the properties of the novelmixtures when the latter are used in fuels.

[0037] The component C comprises conventional additives for mixtureswhich are added to fuels. They are understood as being corrosioninhibitors, demulsifiers, detergents or dispersants, such as amides andimides of polyisobutylsuccinic anhydride, and also carrier oils, such asesters of carboxylic acids or polycarboxylic acids and alkanols orpolyols (cf. DE-A 38 38 918).

[0038] The present invention furthermore relates to fuels for gasolineengines, which contain small amounts of the components A and B.

[0039] Suitable fuels are leaded and unleaded regular and premium-gradegasoline. The gasolines may contain components other than hydrocarbons,for example alcohols, such as methanol, ethanol or tert-butanol, andethers, such as methyl tert-butyl ether.

[0040] The novel fuels contain each of the components A and B in generalin amounts of from 10 to 5,000 ppm, preferably from 50 to 1,000 ppm,based on the total weight. In addition to the components C describedabove, the novel fuels may also contain antioxidants, eg.N,N′-di-sec-butyl-para-phenylenediamine, as stabilizers, eg.N,N′-disalicylidene-1,2-diaminopropane.

[0041] The components A and B can be mixed to give clear, homogeneoussolutions. Fuels to which the latter have been added result insubstantially less valve deposits than the pure fuels. Furthermore, theadditives do not contribute to an octane requirement increase (ORI).

EXAMPLES Preparation Examples Example 1

[0042] Preparation of a Polyether II, where m is 1, n is 24, R¹ isNonylphenyl and D is 1,2-propylene

[0043] 740 g (3.36 mol) of nonylphenol and 55 g of potassiumtert-butylate are reacted with 4.68 kg (80.6 mol) of propylene oxide at130° C. and 4 bar while stirring. After 3.5 hours, the mixture wasworked up to obtain the product. 5.40 kg of the polyether remained.

Example 2

[0044] Preparation of a Polyetheramine I, Where the Variables Have theMeanings Stated in Example 1 and Furthermore R² and R³ are Each Hydrogen

[0045] 362 g (0.3 mol) of the polyether according to Example 1 wereheated with 500 ml of ammonia and 50 g of Raney nickel at 225° C. and ata hydrogen pressure of 280 bar for 4 hours. 330 g of product wereobtained and the degree of amination was 96% (total amine number 44.6 mgKOH/g).

[0046] A polyisobutyamine PIBA having an average molecular weight of1,000 (prepared as described in EP-A 244 616) was used as component A inthe experiments below.

Use Examples

[0047] Mixing Experiments

[0048] The polyether or aminated polyether prepared in Examples 1 and 2,respectively, was mixed with PIBA in the weight ratios 1:1, 2:1 and 1:2,and the homogeneity of the solution was visually assessed. Mixing ratio2:1 1:1 1:2 PIBA + polyether very cloudy 2 phases 2 phases solutionPIBA + aminated clear, homo- clear, homo- clear, homo- polyether geneousgeneous geneous solution solution solution

[0049] Engine Test

[0050] Determination of Valve Deposits in an Opel Kadett according toCEC-F-02-T-79

[0051] In the engine tests, combinations of PIBA with the polyetheraccording to Example 1 or with the aminated polyether according toExample 2 were tested for their efficiency in keeping the intake valvesclean.

[0052] Fuel: unleaded premium-grade European gasoline Amount of additiveAverage valve Product (mg/kg) deposits in mg Basic value (withoutadditive) — 386 PIBA + 200  81 polyether according to Example 1 200PIBA + 200  0 aminated polyether according 200 to Example 2

[0053] The substantially higher efficiency of the novel combination ofPIBA with the aminated polyether compared with the combination of PIBAwith the polyether according to Example 1 is evident.

[0054] Determination of the Octane Requirement Increase ORI GeneralMethod of Measurement:

[0055] The octane requirement increase is measured in a 400 hourlong-term test in a Mercedes-Benz M 102 E engine. In the engine used,the cylinder head is equipped with 4 pressure sensors. These sensors areinstalled so that the pressure membranes are mounted virtually without astraight channel in the wall of the combustion chamber. It is thuspossible to record the pressure in the combustion chamber withoutwhistle vibrations which falsify the result.

[0056] With the indexing apparatus connected for evaluation andconsisting of 4 quartz sensors and a commercial indexing apparatus(AVL-Indiskop), the pressure variations in the range of interest foreach combustion, extending from a crank angle of 300 before the upperdead center to a crank angle of 300 after the upper dead center, can bemonitored. A built-in computer permits the evaluation of the course ofthe combustion. The pressure signals of the individual cylinders can beaveraged and can be evaluated in various computational operations. Ithas proven advantageous to apply the heat law in order to measureknocking in the limiting region.

[0057] This function serves for rapid calculation of the heat curve(=heat liberation per ° crank angle), of the integerated heat curve(cumulative heat liberation) and of the curve for the mean gastemperature. This is a simplified algorithm which calculates, from thepressure variation in the combustion chamber, the energy effectivelysupplied to the gas. The heat actually liberated during the combustionis higher by an amount corresponding to the energy loss through the wall(about 20%).

[0058] The heat liberation in the interval considered is calculated fromthe difference between the actual pressure at the end of the intervaland the pressure value resulting in the case of pure adiabeticcompression/expansion in the interval.

Q ¹⁻² =m·c _(v)(T ₂ −T ₂′) Q¹ ⁻ ² = m ⋅ c_(v)(T₂ − T₂^(′))$T_{2} = {{\frac{P_{2} \cdot V_{2}}{m \cdot R}\quad T_{2^{\prime}}} = \frac{P_{2^{\prime}} \cdot V_{2^{\prime}}}{m \cdot R}}$

$\begin{matrix}{P_{2^{\prime}} = {P_{1^{\prime}}\left( \frac{V_{1}}{V_{2}} \right)}^{n}} & \begin{matrix}{P = \quad {{Actual}\quad {pressure}}} \\{P^{\prime} = \quad {{Pressure}\quad {with}\quad {adiabetic}}} \\{\quad {{compression}/{expansion}}} \\{m = \quad {{Mass}\quad {of}\quad {the}\quad {{fuel}/{air}}}} \\{\quad {mixture}} \\{c_{v} = \quad {{Specific}\quad {heat}}} \\{\quad {v = {constant}}} \\{R = \quad {{Gas}\quad {constant}}} \\{n = \quad {{Polytropic}\quad {exponent}}}\end{matrix} \\{Q_{1 - 2} = {\frac{C_{v}}{R} \cdot {V_{2}\left( {P_{2} - {P_{1}\left( \frac{V_{1}}{V_{2}} \right)}^{n}} \right)}}} & \quad\end{matrix}$

[0059] Approximate values for c_(v) and n.

[0060] c_(v)=0.7+T 0.001·(0.155+A), A=0.1 for gasoline engines$n = {1 + \frac{0.2888}{c_{v}}}$

[0061] The values thus calculated for the energy conversion

[0062] in$\frac{KJ}{{{kg} \cdot {^\circ}}\quad {crank}\quad {angle}}\quad {or}\quad \frac{KJ}{{m^{3} \cdot {^\circ}}\quad {crank}\quad {angle}}$

[0063] clearly indicate disturbances in the energy conversion due tocombustion with knocking.

[0064] It is thus possible to recognize the head threshold with minimumknocking. By means of existing fuels having known octane numbers, theoctane requirement of the engine under certain load conditions can thusbe determined readily and reproducibly.

[0065] Fuel: unleaded premium-grade European gasoline Amount of Octanerequire- additive ment increase Product (mg/kg) (Δ ON) Basic value(without additive) — 3.1 PIBA + 200 8.1 polyether according to Example 1200 PIBA + 200 2.9 aminated polyether according 200 to Example 2

[0066] While the combination of PIBA with polyether leads to an increaseof 4.3 octane numbers and hence an increase by more than 1 octane numbercompared with the value for the fuel without an additive, an octanerequirement increase of only 2.9 was measured for the combination ofPIBA with the aminated polyether.

We claim:
 1. A mixture suitable as a fuel additive and comprisingessentially A) at least one amine, polyamine or alkanolamine, each ofwhich carries a hydrocarbon radical having an average molecular weightof from 500 to 10,000, prepared by hydroformylation of a polyolefin andamination of the resulting aldehyde and alcohol mixture underhydrogenating conditions, and B) at least one polyetheramine of theformula I

where m is 1 or 2 n is from 1 to 100, R¹ is a monovalentC₂-C₃₅-hydrocarbon radical when m is 1 and a divalent C₂-C₃₀-hydrocarbonradical when m is 2, and R² and R³ are each hydrogen, C₁-C₁₂-alkyl,C₅-C₇-cycloalkyl, C₆-C₁₀-aryl, a polyalkyleneamine radical oralkanolamine radical having from 1 to 5 nitrogen atoms, where theradicals may be identical or different and, together with the nitrogenatom to which they are bonded, may form a five-membered or six-memberedring in which further hetero atoms may be incorporated, and D isC₂-C₅-alkylene.
 2. A mixture as claimed in claim 1, wherein thehydrocarbon radical of the component A has an average molecular weightof from 700 to 1,500.
 3. A mixture as claimed in claim 1 or 2, whereinthe hydrocarbon radical of the component A is a polyisobutyl radical. 4.A mixture as claimed in any of claims 1 to 3, wherein, when m is 1, theradical R¹ of component B is phenyl or C₁-C₂₀-alkyl-substituted phenyl.5. A mixture as claimed in any of claims 1 to 4, wherein the radical Dof component B is propylene or butylene.
 6. Use of a mixture as claimedin any of claims 1 to 5 as an additive for fuels for gasoline engines.7. A fuel for gasoline engines, containing small amounts of A) at leastone amine, polyamine or alkanolamine, each of which carries ahydrocarbon radical having an average molecular weight of from 500 to10,000, prepared by hydroformylation of a polyolefin and amination ofthe resulting aldehyde and alcohol mixture under hydrogenatingconditions, and B) at least one polyetheramine of the formula I

where m is 1 or 2 n is from 1 to 100, R¹ is a monovalentC₂-C₃₅-hydrocarbon radical when m is 1 and a divalent C₂-C₃₀-hydrocarbonradical when m is 2, and R² and R³ are each hydrogen, C₁-C₁₂-alkyl,C₅-C₇-cycloalkyl, C₆-C₁₀-aryl, a polyalkyleneamine radical oralkanolamine radical having from 1 to 5 nitrogen atoms, where theradicals may be identical or different and, together with the nitrogenatom to which they are bonded, may form a five-membered or six-memberedring in which further hetero atoms may be incorporated, and D isC₂-C₅-alkylene.